Update portfolio dataframe condition in app.py for improved null handling

- Changed the condition for displaying 'portfolio_df' to check for None instead of its presence in session state, enhancing the robustness of data display logic.
- This update aims to prevent potential errors and improve user experience by ensuring that only valid portfolio data is shown.

app.py

@@ -216,7 +216,7 @@ with tab1:
                     pass
             st.write('Contest data:')
             st.dataframe(st.session_state['Contest'].head(25))
-            if 'portfolio_df' in st.session_state:
+            if 'portfolio_df' is not None:
                 st.write('Portfolio data:')
                 st.dataframe(st.session_state['portfolio_df'].head(25))
             else:

global_func/load_contest_file.py

@@ -167,7 +167,7 @@ def load_contest_file(upload, type, helper = None, sport = None, portfolio = Non
                 portfolio_df['BaseName'] = 'Backtesting_upload'
                 portfolio_df['EntryCount'] = len(portfolio_df)
                 original_columns = cleaned_df.columns.tolist()
-                portfolio_df = portfolio_df.columns(original_columns)
+                portfolio_df.columns = original_columns
                 cleaned_df = pd.concat([cleaned_df, portfolio_df], ignore_index=True)
             
             # Get unique entry names